fix(plugin-sdk): restore root diagnostic compat

scripts/release-check.ts

@@ -21,6 +21,7 @@ const requiredPathGroups = [
   ["dist/index.js", "dist/index.mjs"],
   ["dist/entry.js", "dist/entry.mjs"],
   ...listPluginSdkDistArtifacts(),
+  "dist/plugin-sdk/compat.js",
   "dist/plugin-sdk/root-alias.cjs",
   "dist/build-info.json",
 ];
@@ -228,6 +229,7 @@ const requiredPluginSdkExports = [
   "resolveChannelMediaMaxBytes",
   "warnMissingProviderGroupPolicyFallbackOnce",
   "emptyPluginConfigSchema",
+  "onDiagnosticEvent",
   "normalizePluginHttpPath",
   "registerPluginHttpRoute",
   "DEFAULT_ACCOUNT_ID",